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The Forest Fire Danger Index (FFDI) is the main measure used in Australia for estimating fire risk. Recent work by the authors showed that the FFDI forms stable state regimes, nominated as fire climate regimes. These regimes shifted to greater intensity in southern and eastern Australia around the year 2000 and, a decade later, further north. Reductions in atmospheric moisture were the primary contributor. These changes have not been fully incorporated into future projections. This paper compares the recent regime shifts with the most recent national projections of FFDI, published in 2015. They show that for most states and regions, the 2030 upper limit is approached or exceeded by the recent shift, except for two states with large arid zones, South Australia and Western Australia. Methods for attributing past changes, constructing projections, and the inability of climate models to reproduce the recent decreases in atmospheric moisture, all contribute to these underestimates. To address these shortcomings, we make some suggestions to modify efforts aiming to develop seamless predictions and projections of future fire risk. [ABSTRACT FROM AUTHOR]

Assessing wildfire regimes and their environmental drivers is critical for effective land management and conservation. We used Landsat imagery to describe the wildfire regime of the north-eastern Simpson Desert (Australia) between 1972 and 2014, and to quantify the relationship between wildfire extent and rainfall. Wildfires occurred in 15 of the 42 years, but only 27% of the study region experienced multiple wildfires. A wildfire in 1975 burned 43% of the region and is the largest on record for the area. More recently, a large wildfire in 2011 reburned areas that had not burned since 1975 (47% of the 2011 wildfire), as well as new areas that had no record of wildfires (25% of the 2011 wildfire). The mean minimum wildfire return interval was 27 years, comparable with other spinifex-dominated grasslands, and the mean time since last wildfire was 21 years. Spinifex-dominated vegetation burned most frequently and over the largest area. Extreme annual rainfall events (> 93rd percentile) effectively predicted large wildfires occurring 2 years after those events. Extreme rainfall is predicted to increase in magnitude and frequency across central Australia, which could alter wildfire regimes and have unpredictable and far-reaching effects on ecosystems in the region's arid landscapes. We describe the wildfire regime of the north-eastern Simpson Desert and the relationship between wildfire extent and rainfall. Extreme rainfall can predict large wildfires that occur 2 years later. Extreme rainfall is predicted to increase in the future, which could alter current fire regimes and threaten natural processes and ecosystems. [ABSTRACT FROM AUTHOR]